Influence of extrusion conditions on microstructure and mechanical properties of Mg-2Gd-0.3Zr magnesium alloy

In general, different extrusion conditions will affect the microstructure of magnesium alloys and further determine the mechanical properties. The effects of extrusion parameters and heat treatment processes such as extrusion speed, pre-forging, annealing time, extrusion ratio and cooling rate on the microstructure, texture evolution and tensile properties of Mg-2Gd-0.3Zr alloys were investigated in this study. Compared with the as-cast alloy, the extrusion process significantly refines the grains and exhibit the rare earth texture. With the increase of extrusion speed and annealing time, the growth of recrystallized grains is accelerated, leading to the increase of elongation. Large pre-forging deformation achieves to refine the grains by promoting recrystallization nucleation, resulting in increased strength of Mg-2Gd-0.3Zr alloy. Decreasing the extrusion ratio or increasing the cooling rate will introduce coarse un-DRXed grains, which transformed the texture into the basal texture. In particular, the effect of rapid cooling on refining the recrystallized grains is also obvious. Different extrusion conditions influence the mechanical properties of the Mg-2Gd-0.3Zr alloy through the grain size, proportion of non-recrystallization region and texture type.